1. Field of the Invention
This invention relates to electronic equipment for use with a communication system connected by a communication bus such as an IEEE 1394 bus, for example. More particularly, this invention relates to electronic equipment or the like including a register for setting transmission and reception channels and an operation means for setting channels to this register and in which the transmission and reception channels can be set arbitrarily and easily.
2. Description of the Related Art
In a communication system connected by a communication bus such as an IEEE 1394 bus, a channel and a band which are bus resources may be maintained and a connection may be made by a virtual plug according to the IEC 61883-1 standard, whereby a video signal, an audio signal and the like can be transferred in the isochronous mode.
However, since conventional electronic equipment comprising the above-mentioned communication system are difficult to actively discover equipment to be connected, any of electronic equipment may use the same channel in advance. Even when there are bands to spare, electronic equipment should take the channel from other electronic equipment or should wait for the available channel until the channel is opened.
The IEC 61883-1 standard has a function (1) capable of setting a channel available in transmission equipment and reception equipment when the transmission is started, and is unable to set a channel without searching equipment to be connected. Also, when the transmission is started, if the channel is not set, then transmission equipment is able to transmit data via a previously-determined channel (default channel) described in a specific transmission setting register. Although this 61883-1 standard has prepared a function (2) capable of designating another channel by rewriting this default channel, this standard is unable to set a channel of reception equipment.
Accordingly, when the above-mentioned function (1) is not in use, if some method of operating a channel is not determined, then it is not possible to execute a transmission using a plurality of channels. This situation may apply for other cases in which a signal to be transmitted is a signal of the same type and a signal of other format as well. Further, when a plurality of channels are not in use, even though different transmission rates are permitted in a bus, data should be transmitted at the lowest transmission rate in order for electronic equipment to match with performances of all sorts of reception equipment.